This invention generally relates to multichannel, pulsed radar systems; and more specifically, to a multichannel, pulsed radar system having a subsystem to select the channel over which to transmit the radar pulses, and to a method of operating such a radar system.
In a pulsed radar system, electromagnetic pulses, usually ultra-high frequency radio waves, are transmitted and then reflected by objects that they encounter. The reflected pulses are received by the radar system, and information about the distance and azimuths of the objects producing the reflections can be derived from the delay between the time a particular pulse is transmitted and the time its reflection is received, as well as the direction of arrival of the reflected pulses.
The ability to receive information from the reflected radar pulses is affected by electromagnetic interference received by the radar system; and this interference, often referred to as jamming, generally includes all electromagnetic signals or energy received by the radar system other than the reflected radar pulses. Such interference may be caused by other electronic equipment or data transmission systems in the vicinity of the radar system, and, especially in the case of radar systems used for military purposes, electronic jamming may be intentionally created for the purpose of interfering with the radar system.
To minimize the effects of jamming, radar systems are often designed so that they may transmit and receive the radar pulses over a multitude of channels. With such a system, if significant interference is being received over one or a group of channels, another channel can be selected to transmit the radar pulses.
The channel over which the radar pulse is to be transmitted can be selected in a variety of ways. In a relatively simple case, the channel having the least amount of measured or estimated interference can be chosen to transmit the radar pulse. As a refinement of this relatively simple case, the interference being received over each channel can be measured or estimated, these raw values can be converted to qualified values that indicate the extent to which the interference affects the ability of the radar system to detect targets over each of the channels of the radar system, and the channel having the best potential to detect targets can be selected to transmit the radar pulses.
With both of the above-outlined general procedures, it is preferred to take a multitude of samples or measurements of the interference being received over each channel of the radar system each time the radar pulse is scanned across an area being monitored. Radar systems are currently available with up to a hundred or more channels; and with a radar system having such a large number of channels, it is difficult, first, to take a multitude of samples or measurements of the interference being received over each of the channels, and second, to process all of the acquired data properly and promptly to select the preferred channel to transmit the radar pulses.